PVC‐clay nanocomposites were prepared by melt blending of the polymer with an organically modified clay, both in the presence and in the absence of di(2‐ethylhexyl) phthalate (DOP). The clay can serve as a plasticizer for PVC in the absence of DOP. The nanocomposites were characterized by using X‐ray diffraction and transmission electron microscopy, and the materials were found to be largely intercalated. Thermal properties were evaluated by using thermogravimetric analysis, and the thermal stability was determined to be variable, depending upon the amounts of clay and DOP that were present. The fraction of polymer that remained at 600°C was significantly reduced in the presence of the clay, a result indicating that the clay had an effect on the course of the degradation of the PVC. The tensile strength of the nanocomposites increased as the fraction of clay increased, and the addition of a small amount of clay increased the elongation, but when additional clay was added, the elongation decreased.

Poly(vinyl chloride) (PVC)–clay nanocomposites were prepared by melt blending using a sodium montmorillonite clay. The nanocomposites were characterized by X‐ray diffraction and transmission electron microscopy techniques. The best description of these materials is as mixed immiscible‐intercalated nanocomposites. Mechanical testing showed some improvement in the mechanical properties of the nanocomposites relative to those of the virgin polymer. Cone calorimetry showed that the presence of the clay had an advantageous effect on the fire and smoke properties of the polymer.